Biodiesel are the mixtures of fatty acid esters synthetized by vegetable oils, animal fat or long chain fatty acids with methanol or other low carbon alcohol. Biodiesel is an environmental friendly renewable fuel, and it can play a great role in solving the problems of energy shortage and environmental pollution. The homogeneous catalysts are mainly used in the transesterification to produce biodiesel. However, the high quality requirement to raw materials is necessary when using homogeneous catalysts, and ...